Digital lighting technologies, i.e., illumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offer a viable alternative to traditional fluorescent, HID, and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent advances in LED technology have provided efficient and robust full-spectrum lighting sources that enable a variety of lighting effects in many applications. Some of the fixtures embodying these sources feature a lighting module, including one or more LEDs capable of producing different colors, e.g., red, green, and blue, as well as a processor for independently controlling the output of the LEDs in order to generate a variety of colors and color-changing lighting effects.
Lighting effects projected onto surfaces by light sources such as LEDs may exhibit various lighting properties depending on the nature of the surfaces. For example, light emitted by a lighting unit (e.g., a luminaire) onto one surface may be reflected differently than the same light emitted by the same lighting unit (or the same type of luminaire) onto another surface. In some cases, the two different instances of reflected light may appear differently, e.g., to a human eye.
There may be scenarios in which it is desirable that light reflected from different surfaces be relatively uniform, or that light reflected from a particular surface has one or more selecting properties. Some lighting units may already be configurable to adjust various properties of light they emit. However, equipping such a lighting unit with components necessary to automatically calibrate its light, such as a light sensor (e.g., a camera), may be prohibitively expensive and/or impracticable. Thus, there is a need in the art to provide methods and apparatus for adjusting one or more properties of light emitted by a lighting unit, without adding components to that lighting unit, so that when light emitted by that lighting unit is reflected off a surface, it satisfies one or more lighting property criteria.